The skin is the largest organ in the human body and perhaps the only one that generally receives the most care and attention. We clean it daily with branded cleaners and soaps; Moisturize it with exotic, scented creams and lotions; and protect it with sunscreens that promise a high sun protection factor.
Skin care is a booming market worth $192.8 billion in 2025. As more people seek improved appearance through skin care, the market is expected to reach $432.1 billion by 2035. Although demand for natural and organic skin care is increasing, market concentration is low ($14.09 billion).
With much of the skincare industry still dominated by affordable synthetic skincare and the number of people seeking “glowing skin” increasing, a silent threat lurks among users: disruption of the skin ecosystem.
Human skin and microorganisms
An adult's skin, with hair follicles and channels for oil and sweat, has a surface area of at least 30 m². This exceeds the floor area of some houses in Tokyo, Japan, where the area can be as little as 8-15 m². Various microorganisms – bacteria, fungi, mites and viruses – live in the extensive skin space and form a complex skin microbiome.
Human skin is a living ecosystem: a complex environment rich in oil, sweat and skin cells. The skin's constant supply of lipids, salts, water, amino acids, lactic acid and proteins shapes the skin's microbiome.
The skin microbiome is a dynamic community of microorganisms that thrive in different regions of the skin. A person's intrinsic factors – genetics, gender, age and ethnicity – and the external environment – hygiene, diet, pollution and synthetic products – influence the skin's microbial diversity and abundance.
The member species of the skin's microbial community constantly interact and work together to fight off pathogens. A healthy skin microbiome supports skin health and systemic immunity. Therefore, any disruption of this delicate ecosystem by conventional skin care products disrupts the healthy balance of the microbiome and affects the health of the skin.
Microbiome-boosting skin care
Social media has influenced the use of skin care products, many of which are still synthetic formulations. Basic ingredients in skin care products—such as kojic acid (an active ingredient), parabens (preservatives), and hyaluronic acid (a serum)—reduce microbial diversity by inhibiting the growth of beneficial skin inhabitants.
Reduced microbial diversity (unhealthy skin), often due to overuse of products, promotes opportunistic pathogens that exploit reduced alertness, leading to skin diseases.
Microbiome-enhancing skin care is an innovative approach to improving skin appearance and treating skin diseases. These products include probiotics, postbiotics or prebiotics. Although their functions are different, they help achieve microbial balance and support skin health.
Friendly bacteria
Over the last decade, interest in topical probiotics has increased worldwide. These are carefully selected live microbial formulations that are applied directly to the skin and improve its health. Live or disabled Bifidobacterium And Lactobacilli spp.are popular probiotics for skin care.
Research shows that topical probiotics treat acne and atopic dermatitis by restoring the lost diversity of skin's own microorganisms and strengthening the skin's protective barrier. The probiotic used, usually bacteria, invades the pathogen-infected space and produces biochemicals, including antimicrobials, that deter pathogens and reduce skin inflammation.
Probiotics have now also found their way into basic cosmetics. The latest skincare trend to combat photoaging and skin aging, including wrinkles and hyperpigmentation, is topical probiotics.
Sun exposure (ultraviolet radiation) triggers photoaging (sun damage) by accelerating the production of reactive oxygen species and damaging skin integrity. In addition, UV radiation can disrupt the diversity of the skin microbiome.
Clinical studies have shown that topical probiotics mitigate UV-related damage and oxidative stress. Katlein França, a dermatologist based in Miami, USA, explains how applied probiotics slow down photoaging: by inhibiting enzymes that break down the skin's structural proteins, producing antioxidant and collagen-boosting biomolecules, restoring the skin's acidic pH, improving skin barrier function and gradually promoting microbial balance.
In addition, the biomolecules produced by these “transplanted” bacteria, including organic acids, provide cosmetic effects: retention of skin moisture, improved skin texture and skin lightening.
What are postbiotics?
Postbiotics are the biomolecules or metabolic byproducts of probiotics. These bioactive molecules affect humans and the microorganisms that live within them.
Therefore, these microbial metabolites can be applied topically (as formulations) to achieve similar results to topical probiotics. Postbiotic-based skin formulations, as they are called, mimic the benefits of topical probiotics without the need to maintain healthy microbial cells and storage conditions. Therefore, they are stable and relatively safer for use on people with skin diseases or sensitive skin.
Postbiotics made from carefully selected probiotics are used in skin care products as moisturizers, serums and cleansers. Postbiotics such as antimicrobials (e.g. bacteriocin), short-chain fatty acids (e.g. butyrate), organic acids (e.g. lactic acid) and fermentative bioactives (e.g. lysates) promise therapeutic and cosmetic effects.
Feeding the inhabitants of the skin
The skin naturally supplies its inhabitants with nourishment in the form of oil, sweat and dead skin cells. However, pollution, UV radiation and the use of harsh cleaning products can destroy this natural food and make it difficult for the microbiome to thrive.
Prebiotics supplement the microenvironment that nourishes the skin's microbiome. Prebiotics in skin care are usually complex, indigestible carbohydrates (oligosaccharides) such as inulin. These indigestible substrates are consumed (fermented) by the microbiome to produce skin-friendly products (postbiotics).
Prebiotic skin care that promotes the growth of resident microbes can also improve the microbiome, thereby helping to relieve acne, promote wound healing, reduce photoaging, and improve skin hydration and brightness.
Is this all good news?
Although the potential benefits of microbiome-enhancing skin care are promising, some questions remain unanswered, especially since cosmetics are not as strictly regulated as pharmaceuticals. Who can use these products? Are the benefits consistent for all ethnicities and regions? Are the product claims, particularly their effectiveness and safety, supported by well-founded clinical studies?
Currently, many skin care products are not necessarily labeled as “probiotic.” Most contain postbiotics or prebiotics, which are easier to stabilize and formulate than live bacteria. Richard Gallo of UC San Diego's Department of Dermatology expresses concern about misleading, bold claims made by some in the probiotics market.
While microbiome-centered skin care is a laudable innovation, clearer regulations, stronger clinical validation, and defined guidelines for safety and use are still needed.
(Smruthi Prabhu is an independent science writer based in Mangalore. smruthigp@gmail.com)